The pH and composition of fluids and materials vary in different compartments of the gastro-intestinal tract, such as the esophagus, the stomach, the duodenum, and the colon. Normally, reflux of material from one compartment to another compartment more proximal to the mouth (such as duodeno-gastric reflux or gastro-esophageal reflux) may occur on a limited basis. However, in the case of certain abnormalities and progressive diseases, reflux of material (such as secreted components, digestive components, metabolites, and white blood cells) may be more prevalent than normal. The degree to which such components may cause physical damage depends not only on pH, but also on the presence of specific ingredients such as components of bile acid and pancreatic juice. Such components may however be deleterious only in certain activated stages defined by the pH of the gastro-intestinal compartment, or the pH of the fluid that the component is in.
This invention is a method and a system (comprising a catheter, a recording device and an analysis software package) which for the first time can record on an ambulatory basis both the pH of, and presence of various substances in, the gastro-intestinal tract, and thereby ascertain if a patient is exposed to an excessive amount of agents in a deleterious active state. Substances are identified by monitoring their distinctive light absorption and fluorescence characteristics.
Ambulatory recording of pH has become a common procedure to diagnose duodeno-gastric and gastro-esophageal reflux disease. One commonly used system for this purpose is the Synectics Liberty.TM. System. This comprises a patented single crystal antimony pH sensor (see U.S. Pat. No. 4,119,498), a digital recorder (the Synectics Digitrapper.TM.), and a copyrighted software analysis package (the Synectics EsopHogram.TM. package). The U.S. headquarters of Synectics Medical, Inc. are at 1425 Greenway Drive, Suite 600, Irving, Tex. 75038. The world headquarters of Synectics Medical AB are at Renstiernas Gata 12, S-116 28 Stockholm, Sweden.
Current ambulatory methods of monitoring pH do not give indications of the type of components that may be included in the monitored fluid, even though, for instance, an alkaline shift in gastric pH may indicate the possible presence of refluxed bile acid.
Fiber optic recording of bilirubin in gastric juice by means of measuring the absorption of electromagnetic radiation for at least two discrete wavelengths of said radiation has been taught in U.S. Pat. No. 4,976,265 by Falcial et al. However, this patent does not describe the measurement of a continuous spectra; it does not describe the measurement of both pH and bilirubin; nor does it describe the measurement of fluorescence; and it does not describe the use of pH as a means to estimate the possibly deleterious effect of bile acid (which is active only in the pH range of 5 to 8).
Clarke described in U.S. Pat. No. 5,054,487 a system for-non-invasive material analysis, especially for liquids such as blood, using an illumination source with a plurality of discrete wavelengths and measuring the intensity of reflected light. This patent fails, however, to describe any measurement of gastric juice. Nor does it describe measurements of continuous wavelengths. Nor does it describe measurements of fluorescence. Nor does it describe any combined measurement of the contents of the gastric juice and pH. Nor does it describe the method of using pH as an indicator, whether the measured components are active or not.
Robinson et al. teaches in U.S. Pat. No. 4,975,581 a "Method Of And Apparatus For Determining The Similarity Of A Biologic Analyte From A Model Constructed From Know Biological Fluids." This invention describes a preferred embodiment for noninvasive measurement of blood glucose. Robertson mentions that the device can also be used for measuring alcohol, ketoses, fatty acids, cholesterol, lipoproteins, triglycerides, while blood cells, albumin, blood urea nitrogen, creatinine, concurrent medications such as drugs and any other infrared absorptive components present in a biological analyte fluid. All of the above components indicate that Robinson is focusing on measuring blood and blood components non-invasively.
Robertson also describes an alternative embodiment where interstitial fluid (fluid in between cells) and subdermal fluids are monitored. This is clearly also for similar applications where it is thought that glucose levels should control an insulin pump in an automatic loop, something that will be of great benefits to diabetics.
it In addition, Robertson describes an embodiment in which a fiber is inserted in the blood for direct measurements and it is clear that Robinson's intention is to measure similar components as described above.
Finally, Robertson describes an embodiment where biological sample fluid in internal organs (such as the glucose dependent brain or liver) is irradiated by several wavelengths in a near-infrared spectrum; and it is also understood that in these embodiments such components will be measured. Nowhere in Robinson is it described to measure the contents of the gastro-intestinal canal, which would be a different embodiment not thought of by Robinson. Nowhere is it described to use fluorescence as a measurement technique, nor to combine spectrophotometric and fluorescence measurements in one instrument for simultaneous measurement of both absorption and fluorescence. Nowhere is it described to use sweeping pulses of continuous spectra emitted from a set of RGB, near-infrared and infrared light emitting diodes in such a way that the reflective response in addition to the fluorescence response can be scanned on a continuous basis, thus making an array of infrared to optical electrical transducers redundant. Nowhere is it mentioned to measure pH simultaneously with the prevalence of enzymatic compounds to evaluate whether they are in an active state or not.
Other efforts to measure components of gastric juice include intra-gastro-intestinal catheters with other ion specific sensors such as sodium electrodes. Said ion specific sensors may come to be used as an adjunct to the present invention, as a validation and enhancement of the findings made with the present invention.